java“commitNow（）”和“postDelayed”是如何让这段代码工作的？

Question

我试着做一些零碎的工作。我在布局中放入了一个recyclerview布局，并在片段的onCreateView中初始化了recyclerview。 最后，我将recyclerview的pos动态设置为其项目

我有这样的代码，使它能够正确地与commitNow和postDelayed一起工作，即使延迟为0毫秒，但我不知道为什么：

        getSupportFragmentManager()
                .beginTransaction()
                .replace(R.id.parentLayout, popupFragment)
                .commitNow();
        new Handler().postDelayed(()->popupFragment.show(), 0);

但我试过：

        getSupportFragmentManager()
                .beginTransaction()
                .replace(R.id.parentLayout, popupFragment)
                .commitNow();
        popupFragment.show();

        getSupportFragmentManager()
                .beginTransaction()
                .replace(R.id.parentLayout, popupFragment)
                .commitNowAllowingStateLoss();
        popupFragment.show();

        getSupportFragmentManager()
                .beginTransaction()
                .replace(R.id.parentLayout, popupFragment)
                .runOnCommit(()->popupFragment.show())
                .commitNowAllowingStateLoss();

        getSupportFragmentManager()
                .beginTransaction()
                .replace(R.id.parentLayout, popupFragment)
                .runOnCommit(()->popupFragment.show())
                .commitNow();

它们都有一个未初始化的高度

根据我的猜测，这是关于postDelayed使代码在下一个循环中运行，然而，runOnCommit似乎也会先进行提交，然后再运行可运行的，为什么这不起作用

Answer 1

如果您想要一个“弹出”片段，建议您像这样利用AlertDialog类（并从onCreateView中重构代码，因为您不能保证从onCreateView中引用活动）：

@Override
public void onViewCreated(View view, Bundle onSaveInstanceState) {
    super.onViewCreated(view, onSaveInstanceState);
    AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
    LayoutInflater inflater = LayoutInflater.from(getActivity());
    View popupFragmentsResourceView = inflater.inflate(R.layout.fragment_popup_view, null);
    builder.setView(popupFragmentsResourceView);
    //grab controls here
    //RecyclerView rv = popupFragmentsResourceView.findViewById(R.id.some_id);
    //rv.setAdapter(new CustomAdapter(getActivity));
    //set a click button for your dialog builder
    builder.show();
}